44 
Greville_, on Neiv Diatoms. 
I have much pleasure in dedicating this remarkable and 
ornate species to my friend^ Mr. TufFen West^ the unrivalled 
illustrator of the Diatomacess^ and who is well acquainted 
with the nature of the objects themselves. It is allied to 
Triceratium castellatum, described by himself, from the same 
deposit_, in the eighth volume of the ^ Transactions of the 
Microscopical Society/ but is, in several important cha- 
racters, perfectly distinct. Like most of the species of Tri- 
ceratia discovered in this mine of novelties, it is excessively 
rare. I have only met with six specimens. 
Triceratium Barbadense, n. sp., Grev. — Sides of the frustule 
gently concave ; angles broadly rounded_, separated from the 
centre by transverse lines ; whole valve closely and minutely 
punctate. Distance between the angles '0016''. (Fig. 12.) 
Hab. Barbadoes deposit ; excessively rare. 
Allied to T. castellatum, but differs in the form ; the sides 
of the valve not being nearly so deeply concave, and the 
angles, instead of swelling into segments of circles^ -being 
merely broadly rounded. 
Triceratium nitidum, n. sp., Grev. — Sides of frustule rather 
deeply concave, angles ovate, separated from the centre by 
transverse lines ; whole valve punctate; puncta of the central 
space radiating, and becoming conspicuous as they reach the 
margin. Distance between the angles, -0014". (Fig. 13.) 
Hab. Barbadoes deposit ; extremely rare. 
I am not aware of any described species for which this can 
be mistaken. A good character exists in the puncta of the 
centre, which radiate in single lines, becoming gradually 
larger and the lines more distinct as they approach the 
margin. 
Triceratium cellulosum, n. sp., Grev. — Sides of the valve 
straight ; angles with pseudo-nodules, obtuse, separated from 
the centre by transverse lines ; centre and angles coarsely 
and irregularly cellulose ; cellules of the former more or less 
ovate or oval, and disposed in a radiating direction, though 
not in lines ; those of the latter in rows parallel with the sepa- 
rating line. Distance between the angles '0026". (Fig. 14.) 
Hab. Barbadoes deposit ; exceedingly rare. 
Large and robust, as compared with many of the Barbadoes 
species ; and so peculiar in its characters as to be instanta- 
neously recognised. The cellules of the angles are somewhat 
quadrate, and hence those parts of the valve have a sort of 
cancellated aspect. The lines which separate the angles 
from the central area appear as linear spaces left unoccu- 
pied by the cellules. 
Murray fi eld, Edinburgh; January 15tli, 1861. 
